To be clear: You can draw conclusions about a statistical population without prejudging the invdividual. Very basic statistics.
By the way: My thesis is that Radiohead ruined the audience much more than the Arctic Monkeys could ever do.
Anyway, I'd be happy to see Arctic Monkeys confirmed. Every Primavera visitor should be more than happy about not being "forced" to watch the biggest headliner in the fields of Mordor. And so am I.
And last but not least: Welcome on board!

Mmh, I nearly sure they still could play Pitchfork. Anyway, Ray Ban would be a perfect fit too.
I attended to both of these concerts (Oh Sees played that sunday Apolo-slot in 2015) and they we're incredibly awesome. Also the Interpol pre-festival-gig at Sala Apolo. Hopefully something like that returns in 2018 after the break in 2017. It was much better for me than the "Unexpected Primavera" stuff last year (though that Mogwai gig was really beautiful).

It's kind of funny how so many people here are following some of shittiest sources you can possibly rely to. "I know a friend who has a brother who is the bassist of Arctic Monkeys..." I mean come on...wtf?!
Finally the point where we need some substantial informations is more than reached. Everything else leads nowhere.
My personal more or less likely wishlist:
Deerhunter and/or Built To Spill for Ray-Ban.
(Thee) Oh Sees and/or Titus Andronicus for Sala Apolo.
Belle and Sebastian and/or The Breeders for Primavera/ATP.
Rodriguez and/or Thundercat for Auditorium.
Unknown Mortal Orchestra for Pitchfork late slot.
My Bloody Valentine as (surprise) headliner.
+ some Post-Rock, some Jazz, something to dance to for Ray-Ban and some nice oldschool hip-hop.